Right ventricular dysfunction after intracardiac repair of congenital heart defects is common and is frequently responsible for the perioperative morbidity and mortality associated with repair. Animals undergoing pulmonary artery banding develop pure right ventricular hypertrophy (RVH), similar to that seen in many congenital cardiac defects. It was the purpose of this study to observe the change in right and left ventricular performance in the heart with RVH before and after global ischemia. In addition, it was hypothesized that removal of obstruction to RV outflow in chronic RVH animals would protect the postischemic performance of both ventricles. RVH was induced by pulmonary artery banding in puppies. After 6 months, the RVH group and an aged matched control group were subjected to global ischemia on 28 degrees C cardiopulmonary bypass with cold crystalloid cardioplegia for 2 hours. In the RVH group, the PA outflow tract was repaired with a pericardial patch. Myocardial function and metabolism were determined for 4 hours after reperfusion. In both control and RVH groups, postischemic cardiac output and ventricular function were significantly lower than their preischemic values in both ventricles. However, no difference in these values was observed between control and RVH group. Aortic and LV pressure and heart rate remained unchanged throughout the study. There were no changes in RV MVO(2) and lactate consumption either in baseline measurement or during reperfusion in both groups. Therefore, postischemic RV and LV performance can be preserved during hypothermic cardioplegic arrest when RV obstruction is relieved in chronic RVH dogs.